Development of a numerical model for predicting the volatilization flux from unsaturated soil

2021 ◽  
Author(s):  
Monami Kondo ◽  
Yasuhide Sakamoto ◽  
Takeshi Komai ◽  
Yoshishige Kawabe ◽  
Kengo Nakamura ◽  
...  
Keyword(s):  
Unsaturated Soil ◽  
Soil Moisture Content ◽  
Surface Soil ◽  
Transport Phenomena ◽  
Soil Surface ◽  
Two Phase ◽  
Dynamic Variations ◽  
Mercury Transport ◽  
Unsaturated Condition ◽  
And Diffusion

<p>In recent years, exposure to volatile chemical substances (VCSs) from contaminated soil has become a serious problem so it has become increasingly important to study the transport phenomena of VCSs. In this study we focused on the transport phenomena of VCSs at the boundary layer between the soil surface and the atmosphere, and defined it as volatilization flux, which express the amount of volatilized substances per unit volume per unit time. In order to estimate the phenomena of mercury transport in unsaturated soil and mercury released from soil to the atmosphere, it is necessary to consider in detail the spatiotemporal fluctuations of factors that affect the volatilization of mercury and the physical transport phenomena in soil.</p><p>The present study developed a model for predicting the volatilization flux from the unsaturated soil contaminated by VCSs. The model considers a series of phenomena under the unsaturated condition such as gas-liquid two-phase flow consisting of convection and diffusion. The effects of various transport phenomena on the surface soil on changes in the magnitude of this flux due to variations in meteorological factors such as temperature and soil moisture content were quantitatively evaluated. This developed prediction model can be utilized to estimate dynamic variations in the flux under real-environmental conditions.</p>

scholarly journals Development of a Model for Predicting the Volatilization Flux from Unsaturated Soil Contaminated by Volatile Chemical Substances

2021 ◽  
Author(s):  
Monami Kondo ◽  
Yasuhide Sakamoto ◽  
Yoshishige Kawabe ◽  
Kengo Nakamura ◽  
Noriaki Watanabe ◽  
...  
Keyword(s):  
Unsaturated Soil ◽  
Surface Soil ◽  
Ground Surface ◽  
Weather Factors ◽  
Chemical Substances ◽  
Multi Phase Flow ◽  
Phase Liquid ◽  
Multi Phase ◽  
Adsorption Desorption ◽  
Unsaturated Condition

AbstractThis work developed a model for predicting the volatilization flux from the unsaturated soil contaminated by volatile chemical substances (VCSs) such as mercury and benzene. The model considers a series of phenomena under the unsaturated condition such as multi-phase flow consisting of a non-aqueous phase liquid, water, and gases together with the permeation of rainfall into the surface soil, the volatilization/condensation of VCSs, and the adsorption/desorption of VCSs. On this basis, this work clarified a mechanism for the generation of a volatilization flux at the ground surface. In addition, the effects of various transport phenomena in the surface soil on the magnitude and seasonal changes in this flux due to variations in weather factors such as rainfall level, temperature, and air pressure were quantitatively evaluated. This newly developed prediction model can be utilized to estimate dynamic variations in the flux under real-environmental conditions.

LYSIMETERS WITH RAINFALL AND SOIL WATER CONTROL

1971 ◽  
Vol 2 (2) ◽  
pp. 79-92 ◽  
Author(s):  
K. J. KRISTENSEN ◽  
H. C. ASLYNG
Keyword(s):  
Soil Moisture Content ◽  
Soil Depth ◽  
Irrigation System ◽  
Drainage System ◽  
Soil Surface ◽  
Trickle Irrigation ◽  
Water Control ◽  
Radiation Equipment ◽  
Different Depths ◽  
Growth Experiments

The lysimeter installation described comprises 36 concrete tanks each with a soil surface of 4 m2. The installation is useful for plant growth experiments under natural conditions involving different treatment combined with various controlled water supplies. The ground installation is at least 20 cm below the soil surface and tillage can be done with field implements. The lysimeter tanks are provided with a drainage system which can drain the soil at the bottom (100 cm depth) to a tension of up to 100 cm. A constant ground-water table at less than 100 cm soil depth can also be maintained. The soil moisture content at different depths is determined from an underground tunnel by use of gamma radiation equipment in metal tubes horizontally installed in the soil. Rainfall is prevented by a movable glass roof automatically operated and controlled by a special rain sensor. Water is applied to the soil surface with a special trickle irrigation system consisting of a set of plastic tubes for each lysimeter tank and controlled from the tunnel. Fertilizers in controlled amount can be applied with the irrigation water.

A Ternary, Two-Phase, Mathematical Model of Oil Recovery With Surfactant Systems

1984 ◽  
Vol 24 (06) ◽  
pp. 606-616 ◽  
Author(s):  
Charles P. Thomas ◽  
Paul D. Fleming ◽  
William K. Winter
Keyword(s):  
Mathematical Model ◽  
Oil Recovery ◽  
Arbitrary Number ◽  
The Other ◽  
Phase System ◽  
Chemical Flooding ◽  
Two Phase ◽  
Oil Displacement ◽  
Surfactant Systems ◽  
And Diffusion

Abstract A mathematical model describing one-dimensional (1D), isothermal flow of a ternary, two-phase surfactant system in isotropic porous media is presented along with numerical solutions of special cases. These solutions exhibit oil recovery profiles similar to those observed in laboratory tests of oil displacement by surfactant systems in cores. The model includes the effects of surfactant transfer between aqueous and hydrocarbon phases and both reversible and irreversible surfactant adsorption by the porous medium. The effects of capillary pressure and diffusion are ignored, however. The model is based on relative permeability concepts and employs a family of relative permeability curves that incorporate the effects of surfactant concentration on interfacial tension (IFT), the viscosity of the phases, and the volumetric flow rate. A numerical procedure was developed that results in two finite difference equations that are accurate to second order in the timestep size and first order in the spacestep size and allows explicit calculation of phase saturations and surfactant concentrations as a function of space and time variables. Numerical dispersion (truncation error) present in the two equations tends to mimic the neglected present in the two equations tends to mimic the neglected effects of capillary pressure and diffusion. The effective diffusion constants associated with this effect are proportional to the spacestep size. proportional to the spacestep size. Introduction In a previous paper we presented a system of differential equations that can be used to model oil recovery by chemical flooding. The general system allows for an arbitrary number of components as well as an arbitrary number of phases in an isothermal system. For a binary, two-phase system, the equations reduced to those of the Buckley-Leverett theory under the usual assumptions of incompressibility and each phase containing only a single component, as well as in the more general case where both phases have significant concentrations of both components, but the phases are incompressible and the concentration in one phase is a very weak function of the pressure of the other phase at a given temperature. pressure of the other phase at a given temperature. For a ternary, two-phase system a set of three differential equations was obtained. These equations are applicable to chemical flooding with surfactant, polymer, etc. In this paper, we present a numerical solution to these equations paper, we present a numerical solution to these equations for I D flow in the absence of gravity. Our purpose is to develop a model that includes the physical phenomena influencing oil displacement by surfactant systems and bridges the gap between laboratory displacement tests and reservoir simulation. It also should be of value in defining experiments to elucidate the mechanisms involved in oil displacement by surfactant systems and ultimately reduce the number of experiments necessary to optimize a given surfactant system.

Experimental Determination of Statistical Properties of Two-Phase Turbulent Motion

1960 ◽  
Vol 82 (3) ◽  
pp. 609-621 ◽  
Author(s):  
S. L. Soo ◽  
H. K. Ihrig ◽  
A. F. El Kouh
Keyword(s):  
Gas Phase ◽  
Tracer Diffusion ◽  
Statistical Properties ◽  
Solid Particles ◽  
Turbulent Motion ◽  
Two Phase ◽  
Gaseous State ◽  
Diffusion Technique ◽  
And Diffusion

Experimental methods for the determination of certain statistical properties of turbulent conveyance and diffusion of solid particles in a gaseous state are presented. Methods include a tracer-diffusion technique for the determination of gas-phase turbulent motion and a photo-optical technique for the determination of motion of solid particles. Results are discussed and compared with previous analytical results.

Using soil surface gray level to determine surface soil water content

2010 ◽  
Vol 53 (10) ◽  
pp. 1527-1532 ◽  
Author(s):  
YuanJun Zhu ◽  
YunQiang Wang ◽  
MingAn Shao
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Surface Soil ◽  
Soil Surface ◽  
Gray Level

Laboratory and field studies on the degradation of fipronil in a soil

Soil Research ◽  
2002 ◽  
Vol 40 (7) ◽  
pp. 1095 ◽  
Author(s):  
Guang-Guo Ying ◽  
Rai Kookana
Keyword(s):  
Soil Moisture ◽  
Half Life ◽  
Soil Moisture Content ◽  
Soil Surface ◽  
Field Studies ◽  
Transformation Product ◽  
Laboratory Studies ◽  
The Third ◽  
High Soil Moisture ◽  
Sulfone Derivatives

Degradation of a new insecticide/termiticide, fipronil, in a soil was studied in the laboratory and field. Three metabolites of fipronil (desulfinyl, sulfide, and sulfone derivatives) were identified from soils after treatment. Laboratory studies showed that soil moisture content had a great effect on the degradation rate of fipronil and products formed. High soil moisture contents (>50%) favored the formation of a sulfide derivative of fipronil by reduction, whereas low soil moisture (<50%) and well-aerated conditions favored the formation of fipronil sulfone by oxidation. Microorganisms in soil accelerated the degradation of fipronil to sulfide and sulfone derivatives. The third transformation product, a desulfinyl derivative, was formed by photodecomposition of fipronil in water and on the soil surface under sunlight. The desulfinyl derivative degraded rapidly in field soils with a half-life of 41–55 days compared with an average half-life of 132 days for fipronil. The half-life of the 'total toxic component' (fipronil and its metabolites) in field soil was 188 days on average.

The Application of Numerical Simulation to Liquid Pipeline Leakage at LNG Terminal in China

2020 ◽  
Author(s):  
Zhichao Guo ◽  
Zhaoci Li
Keyword(s):  
Numerical Simulation ◽  
Liquid Phase ◽  
Natural Gas ◽  
Diffusion Process ◽  
Gas Phase ◽  
Stokes Equations ◽  
Response Strategy ◽  
Movement Trajectory ◽  
Two Phase ◽  
And Diffusion

Abstract In 2018, China’s natural gas import reached 90.39 million tons, and the liquefied natural gas (LNG) import was 53.78 million tons, accounting for 59.5% of total natural gas imports. With the construction of LNG terminals, more studies on the leakage of LNG storage and transportation facilities have emerged to prevent catastrophic consequences such as explosions and frostbite. However, most of previous researches focused on gas pipeline leakage after LNG gasification, and few of those have been done on LNG liquid pipeline leakage. In this paper, Fluent software is used to numerically simulate the process of LNG liquid pipeline leakage. After the occurrence of LNG leakage, it will suffer the process of endothermic, evaporation, and diffusion, which is considered as a two-phase diffusion process. The Euler-Lagrangian method is introduced to simulate the diffusion process of gas phase and liquid phase separately. In the simulation, the liquid phase is regarded as discrete droplets for discrete processing. The movement trajectory, heat transfer process and evaporation process of each droplet are tracked respectively. Different from the liquid phase, the gas phase is regarded as a continuous phase and the Navier-Stokes equations are adopted for calculation. Thereafter, coupling calculations of two phase are performed to determine the concentration field and temperature field of the LNG liquid pipeline leakage. As a supplement to this research, the influence of wind speed on LNG leakage and diffusion process is analysed in detail. Finally, the numerical simulation method is applied to a coastal LNG terminal in northern China to determine the distribution of natural gas concentration and temperature, as well as delimit the combustion range. The results can provide scientific reference for the delimitation of risky zones and the formulation of emergency response strategy.

Mapping of tank silt application using Sentinel-2 images over the Berambadi catchment (India).

2021 ◽  
Author(s):  
Cécile Gomez ◽  
Dharumarajan Subramanian ◽  
Philippe Lagacherie ◽  
Jean Riotte ◽  
Sylvain Ferrant ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Properties ◽  
South India ◽  
Surface Soil ◽  
Soil Surface ◽  
Calibration Data ◽  
Surface Soil Moisture ◽  
Soil Color ◽  
Color Changes ◽  
Sentinel 2

&lt;p&gt;Mapping soil properties is becoming more and more challenging due to the increase in anthropogenic modification of the landscape, calling for new methods to identify these changes. A striking example of anthropogenic modifications of soil properties is the widespread practice in South India of applying large quantities of silt from dry river dams (or &amp;#8220;tanks&amp;#8221;) to agricultural fields. Whereas several studies have demonstrated the interest of tank silt for soil fertility, no assessment of the actual extent of this age-old traditional practice exists. Over pedological contexts characterized by Vertisol, Ferralsols and Chromic Luvisols in sub-humid and semi-arid Tropical climate, this practice is characterized by an application of black-colored tank silt providing from Vertisol, to red-colored soils such as Ferralsols. The objective of this work was to evaluate the usefulness of Sentinel-2 images for mapping tank silt applications, hypothesizing that observed changes in soil surface color can be a proxy for tank silt application.&lt;/p&gt;&lt;p&gt;We used data collected in a cultivated watershed (Berambadi, Karnataka state, South India) including 217 soil surface samples characterized in terms of Munsell color. We used two Sentinel-2 images acquired on February 2017 and April 2017. The surface soil color over each Sentinel-2 image was classified into two-class (&amp;#8220;Black&amp;#8221; and &amp;#8220;Red&amp;#8221; soils). A change of soil color from &amp;#8220;Red&amp;#8221; in February 2017 to &amp;#8220;Black&amp;#8221; in April 2017 was attributed to tank silt application. Soil color changes were analyzed accounting for possible surface soil moisture changes. The proposed methodology was based on a well-balanced Calibration data created from the initial imbalanced Calibration dataset thanks to the Synthetic Minority Over-sampling Technique (SMOTE) methodology, coupled to the Cost-Sensitive Classification And Regression Trees (Cost-Sensitive CART) algorithm. To estimate the uncertainties of i) the two-class classification at each date and ii) the change of soil color from &amp;#8220;Red&amp;#8221; to &amp;#8220;Black&amp;#8221;, a bootstrap procedure was used providing fifty two-class classifications for each Sentinel-2 image.&lt;/p&gt;&lt;p&gt;The results showed that 1) the CART method allowed to classify the &amp;#8220;Red&amp;#8221; and &amp;#8220;Black&amp;#8221; soil with overall accuracy around 0.81 and 0.76 from the Sentinel-2 image acquired on February and April 2017, respectively, 2) a tank silt application was identified over 97 fields with high confidence and over 107 fields with medium confidence, based on the bootstrap results and 3) the identified soil color changes are not related to a surface soil moisture change between both dates. With the actual availability of the Sentinel-2 and the past availability of the LANDSAT satellite imageries, this study may open a way toward a simple and accurate method for delivering tank silt application mapping and so to study and possibly quantify retroactively this farmer practice.&lt;/p&gt;

A synecological account of the Suikerbosrand Nature Reserve. II. The phytosociology of the Ventersdorp Geological System

Bothalia ◽  
1980 ◽  
Vol 13 (1/2) ◽  
pp. 199-216 ◽  
Author(s):  
G. J. Bredenkamp ◽  
G. K. Theron
Keyword(s):  
Plant Communities ◽  
Soil Texture ◽  
Nature Reserve ◽  
Surface Soil ◽  
Soil Depth ◽  
Soil Surface ◽  
Habitat Features ◽  
Species Groups

The vegetation of the Ventersdorp Geological System of the Suikerbosrand Nature Reserve is analysed and classified according to the Braun-Blanquet method. Descriptions of the plant communities include description of habitat features, the identification of differentiating species groups as well as the listing of prominent and less conspicuous species for the tree, shrub and herbaceous layers. The habitat features that are associated with differences in vegetation include altitude, aspect, slope, rockiness of soil surface, soil depth and soil texture.

Examination of the Penetration of Enteric Viruses in Soils under Simulated Conditions in the Laboratory

1985 ◽  
Vol 17 (10) ◽  
pp. 197-199 ◽  
Author(s):  
P. H. Jørgensen
Keyword(s):  
Sewage Sludge ◽  
Unsaturated Soil ◽  
Sandy Loam ◽  
Soil Column ◽  
Enteric Viruses ◽  
Soil Surface ◽  
Coxsackievirus B3 ◽  
Soil Columns ◽  
Sand Column ◽  
Loam Soil

In two different unsaturated soil columns percolated with artificial rainwater under simulated aerated conditions, transport of coxsackievirus B3 and adenovirus 1 below 3.5 cm under the soil surface could not be demonstrated. The viruses were applied to the columns as seeded sewage sludge. Under saturated conditions transport of water-suspended coxsackievirus B3 was faster in a soil column with sandy loam soil than in a diluvial sand column.

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